| Game |
| Result | Moves |
Year | Event/Locale | Opening |
| 26. Petursson vs Vukcevich |
| 0-1 | 25 | 1976 | Reykjavik | A21 English |
| 27. Petursson vs Antoshin |
| 1-0 | 53 | 1976 | Reykjavik | A10 English |
| 28. Petursson vs Keene |
| 0-1 | 26 | 1976 | Reykjavik | A10 English |
| 29. E Vladimirov vs Petursson |
| 1-0 | 54 | 1976 | W/EU-ch U20 7677 | A13 English |
| 30. Petursson vs C Hertan |
 | 1-0 | 18 | 1977 | GHI International | E06 Catalan, Closed, 5.Nf3 |
| 31. Lombardy vs Petursson |
| 1-0 | 50 | 1978 | Reykjavik | D03 Torre Attack (Tartakower Variation) |
| 32. Petursson vs Plaskett |
| 1-0 | 40 | 1978 | EU-ch U20 7879 | A10 English |
| 33. Smejkal vs Petursson |
| 1-0 | 39 | 1978 | Reykjavik | A17 English |
| 34. Browne vs Petursson |
| 1-0 | 29 | 1978 | Reykjavik | A18 English, Mikenas-Carls |
| 35. Petursson vs Larsen |
| 1-0 | 27 | 1978 | Reykjavik | E08 Catalan, Closed |
| 36. Petursson vs A J Mestel |
| ½-½ | 51 | 1978 | Lone Pine | A10 English |
| 37. G Ligterink vs Petursson |
| 0-1 | 28 | 1978 | Lone Pine | B33 Sicilian |
| 38. Petursson vs N Weinstein |
| 1-0 | 57 | 1978 | Lone Pine | A30 English, Symmetrical |
| 39. Miles vs Petursson |
| 1-0 | 33 | 1978 | Lone Pine | D32 Queen's Gambit Declined, Tarrasch |
| 40. Petursson vs Sahovic |
| ½-½ | 28 | 1978 | Lone Pine | E92 King's Indian |
| 41. Petursson vs Janosevic |
| 0-1 | 33 | 1978 | Lone Pine | B39 Sicilian, Accelerated Fianchetto, Breyer Variation |
| 42. Z Mestrovic vs Petursson |
| 0-1 | 42 | 1978 | Lone Pine | D01 Richter-Veresov Attack |
| 43. K Commons vs Petursson |
| ½-½ | 70 | 1978 | Lone Pine | D32 Queen's Gambit Declined, Tarrasch |
| 44. Petursson vs Gheorghiu |
| ½-½ | 47 | 1978 | Lone Pine | A25 English |
| 45. Petursson vs C Van Tilbury |
| 0-1 | 47 | 1978 | GHI open | A13 English |
| 46. Petursson vs K Mokry |
| ½-½ | 41 | 1978 | Wch U20 | E92 King's Indian |
| 47. Petursson vs Yusupov |
| 0-1 | 38 | 1978 | Wch U20 | A25 English |
| 48. Petursson vs Liu Wenzhe |
| 0-1 | 26 | 1978 | Olympiad | B39 Sicilian, Accelerated Fianchetto, Breyer Variation |
| 49. Tringov vs Petursson |
| ½-½ | 48 | 1978 | Olympiad | A07 King's Indian Attack |
| 50. Petursson vs Sax |
| ½-½ | 16 | 1978 | Olympiad | A10 English |
Kibitzing
